Fields I want to link are greyed out.

I have a sheet of all my clients. There are two other sheets I have that I want to link to the Name field in the client sheet.
On one of them I was able to link it.

But when I try to do it in the other sheet, the Company Name field on the right is always greyed out so I can’t select it in the Link Manager.


You may refer to this article for why those greyed out in link and load.